This invention relates to an insulation displacement contact and a method of making connections to wires.
Insulation displacement contacts may be formed from a contact element which is bifurcated so as to define two opposed contact portions separated by a slot into which an insulated wire may be pressed so that edges of the contact portions engage and displace the insulation and such that the contact portions resiliently engage and make electrical connection with the conductor of the wire. Such a contact is described in, for example U.S. Pat. Nos.4,452,502 and 4,405,187.
While, in some cases, making electrical connection to a single wire in the above way is all that is necessary, occasions arise where it would be useful to make connection to more than one wire by inserting the wires, one after the other, into the slot. With a carefully designed contact it may be possible to make connections in this way to two wires, but it is usually impossible to make effective connections to several wires. This arises because, during the process of introducing a first wire into the slot, the contact portions are resiliently deformed, such that the gap between them is to some extent increased. The resultant increase in slot width may still permit an adequate connection to be made to a second wire when inserted into the slot. However, the increased slot width may even be such that the contact portions fail to properly pierce the insulation, or it may otherwise leave the second wire unreliably gripped. This problem becomes worse as more wires are inserted.
The above problem is alleviated in Krone LSA-PLUS connectors by arranging that the contact portions are torsionally twisted during insertion of the wires. That is, the wires are introduced into the slot with their directions of extent arranged at an angle of about 45 degrees to the side to side direction of the slot, so that insertion of the wires tends to deflect contacting edges of the respective contact portions outwardly away from each other, in opposite directions relative to the general plane of the contact. In that case, it is possible to achieve good connection to two wires but even in this construction more than two wires may not be adequately accommodated.
U.S. Pat. No.5,492,484 also describes a particular form of contact that is indicated as being able to terminate more than a single conductor. This is however complicated in form.
It is an object of the invention, in one aspect, to provide a method making electrical connection to a plurality of insulated wires and an electrical connector useful in practising the method.
In one aspect, there is provided a method of making electrical connection to wires having insulated conductors, using a contact element which is bifurcated so as to define two opposed contact portions separated by a slot, in which the wires are positioned in the slot successively, with the directions of extent of the wires, or of groups of commonly aligned ones thereof being alternatively disposed with respect to the side-to-side direction of the slot and such that, as between the or each successive pair of wires in the slot, the angle made between the wires of that pair is greater than that made by one of the wires with respect to the side-to-side direction.
The invention also provides a method of making electrical connection to wires having insulated conductors, using a contact element which is bifurcated so as to define two opposed contact portions separated by a slot, in which the wires are positioned in the slot successively, with the directions of extent of the wires, or of groups of commonly aligned ones thereof, alternatingly arranged at angles which are at opposite sides of the perpendicular to the side to side direction of the slot, so that edges of the contact portions engage and displace the insulation and such that the contact portions resiliently engage and make electrical connection with the conductors of the wires.
The invention also provides an electrical connector having body which supports a contact element which is bifurcated so as to define two opposed contact portions separated by a slot in which insulated wires may be successively positioned so that edges of the contact portions engage and displace the insulation of the wires and such that the contact portions resiliently engage and make electrical connection with the conductors of the wires, wherein the body is provided with wire guide means for guiding the wires during positioning in the slot such that, as between the or each successive pair of wires in the slot, the angle made between the wires of that pair is greater than that made by one of the wires with respect to the side-to-side direction. The wire guide means may be arranged such that wires successively positioned in said slot are disposed in respective first and second dispositions, ones of the wires in said respective first and second dispositions extending at angles to the side to side direction of the slot which are respectively to opposite sides of a perpendicular to the side to side direction.
The contact element may be formed of a generally planar element such that the side to side dimension of the slot is generally aligned with the plane of the contact element.
The wire guide means may be formed as channels arranged to extend at an angle to each other, the connector having means for supporting the insulation displacement contact so that when the insulated wires are entered positioned in the channels, the wires extend angularly with respect to each other for said electrical connection to the conductors thereof by the contact element. The channels may extend inwardly of the body in the same directional sense, but such that the longitudinal directions of extent of these cross. In this case with one channel may be deeper than the other so that an inner one of said wires may first be located in the deeper channel and an outer one of the wires then laid thereover in the less deep channel.
Alternatively, the channel may be disposed in a side wall of the body. The channels may then be sidewardly open for receiving the wires. The contact may be slidable with respect to the body, between a position at which it is at least substantially withdrawn from the channels and a position at which it is moved to make insulation displacement contact with wires received in the channels. The channels may also be peripherally closed, but open at at least one end thereof for longitudinal insertion of the wires.
In a preferred method, the contact portions are subjected to torsional forces during insertion of a said wire, the directions of action of those forces, as arising from positioning of respective wires or groups of wires in said slot, being oppositely directed.
In another aspect, the invention provides a method of making electrical connection between electrically insulated wires and a bifurcated insulation displacement contact in which the wires are so positioned in a slot between opposed contact portions of the contact that the contact portions are subjected to torsional forces during positioning of said wires in the slot, the directions of action of those forces as due to successive ones of the wires in the slot, being oppositely directed.
In another aspect the invention provides an electrical connector having a bifurcated insulation displacement contact having opposed contact portions with a slot therebetween whereby insulated wires may be positioned in the slot such that the contact portions displace the insulation of the wires to make electrical connection to conductors of the wires, the connector having wire guide means for locating the wires with respect to the contact, arranged whereby the positioning of the wires in the slot causes the contact portions to be subjected to torsional forces, the directions of action of those forces, as due to successive ones of the wires when positioned in the slot, being oppositely directed.